某水库大坝挡水坝段坝后渗漏探测及有限元分析

On the seepage detection of water retaining dam section of some reservoir’s dam and its finite element analysis

混凝土坝坝体渗漏影响大坝的安全性和耐久性,危及电器设备正常运行,应及时探查渗漏位置,消除渗漏隐患。为查明某混凝土挡水坝坝后渗漏原因,采用自然电位、跨孔声波、单孔声波、钻孔电视、钻孔取芯、注水试验、压水试验等多种方法对坝体混凝土质量进行检测,并基于检测成果开展有限元分析。检测发现:4号—5号坝段横缝存在渗漏异常,挡水坝段混凝土渗透系数不满足设计抗渗要求,各坝段混凝土存在不同程度蜂窝、离析、空洞和不密实现象,4号坝段520廊道与494廊道存在垂向渗漏通道,5号坝段钻孔之间混凝土存在渗漏通道,且廊道以下及向下游方向混凝土存在渗漏通道。有限元分析结果表明:515 m高程碾压混凝土与常态混凝土交界处为主要渗漏通道。

The seepage of concrete dam affects the safety and durability of the dam and endangers the normal operation of power generation equipment.In order to find out the reason and position of leakage behind the dam,this study uses spontaneous potential method,core sample,pressurized water test,borehole TV,cross hole sonic wave method,single hole sonic wave method,water injection test to detect concrete quality of dam body.The analysis results show that transverse joint exists leakage between 4#dam and 5#dam;the permeability coefficient of concrete in retaining dam section does not meet the design impermeability requirement;there are honeycomb,segregation,cavity,uncompacted phenomenon and low speed area in the concrete of each dam section;there are vertical leakage channels in 520 gallery and 494 gallery of dam Section 4#,there is a seepage channel between the drilled holes of the 5#dam section and a seepage channel below the gallery and in a certain direction downstream.Based on the detection results,finite element analysis shows that the junction between RCC and normal concrete at 515 m elevation is the main leakage channel.